The present disclosure generally relates to vehicle batteries, and more particularly relates to a battery confirmation system and method for confirming a state of charge in a vehicle battery installed in a vehicle, such as immediately before the vehicle exits a manufacturing assembly line and/or plant.
Vehicle manufacturers often desire to confirm that production vehicles are shipped from the manufacturing facility in good condition. This includes confirming that production vehicles are shipped with their vehicle batteries having at least a minimum state of charge. The purpose for such confirmation is to attempt to limit the number of warranty claims related the battery (i.e., prevent under specification batteries from being shipped on new vehicles). One existing method for confirming the state of charge (SOC) in the battery of a production vehicle is the hydrometer check method. In this method, a specific gravity metering device (i.e., a hydrometer), such as a plastic ball with a precisely controlled density, can be used to detect a low state of charge battery based on the specific gravity of the electrolyte contained within the battery.
In particular, the ball can be located in a single cell of the battery. A sight glass window is provided on the battery's outer surface adjacent the single cell so that the ball is viewable when the specific gravity of the battery cell is at a specified level correlated to the density of the ball so that the ball floats. When the ball floats, ball can be seen through the sight glass window, and such sighting is used to indicate that the battery has a sufficient state of charge. Should the specific gravity fall below a predetermined level (e.g., 1.20), the ball will fall and window will turn another color (e.g., black). Visual confirmation of the ball in the sight glass window on the battery, or lack of such visual confirmation, provides an indication of whether the vehicle battery has the sufficient state of charge in that particular cell.
Advantageously, the hydrometer check method supplies an indication of the state of charge of the battery very quickly. That is, the hydrometer check method provides a quick visual indication of whether the battery has a sufficient state of charge. This is particularly beneficial in an assembly line environment where there may be only a very limited amount of time to confirm that the battery is in good condition.
Unfortunately, a drawback of the hydrometer check is that it has been found to be only marginally reliable. For example, most production vehicle batteries contain a plurality of cells (e.g., six cells) but the hydrometer test only occurs in connection with one of the plurality of cells. As a result, the hydrometer test only confirms that the specific gravity of one of the plurality of cells is at a correct level. This can be a problem when there is a variance in the state of charge between cells in a battery. Another drawback of the hydrometer check method is that its margin of error is significant. In particular, the ball may float confirming that the battery is supposedly with an adequate state of charge when in fact the state of charge could be lower than desired. Also, battery related claims currently can be one of the largest warranty items for production vehicles. Such claims can result from production vehicles being shipped from the manufacturing facility with a low state of charge. An additional drawback of the hydrometer method is that there is currently no traceability to the vehicle in which the battery is included. Therefore, the vehicle might be shipped after successful hydrometer check. However, when a later warranty item occurs in connection with the vehicle, there is no way for the vehicle manufacturer to show that the vehicle was shipped with a battery having an adequate state of charge.
Several more accurate battery testing methods are known. However, many of these require the battery to be disconnected from the vehicle and/or are unsuitable for a manufacturing environment. In particular, many battery test methods require expensive equipment and/or more time than is afforded on a vehicle production line.